Natural fiber board panels have a variety of applications. These panels are typically described as medium density fiberboard (MDF), high density fiberboard (HDF) and particleboard. The present invention describes the manufacture of a resilient fibre board made from natural fibers. By introducing resiliency to the panels, products made from the panels have been found to offer better sound attenuation.
To produce wood particleboard, the wood particles, for example wood fibers or wood chips, are glued together by means of an organic adhesive under pressure and at elevated temperature. The most important binders for fiberboard production are urea-formaldehyde resins (UF resins). To produce moisture-resistant wood chipboards, phenol-formaldehyde resins (PF resins) are of great importance.
Melamine-formaldehyde resins (MF resins) are also used for improving the moisture resistance of wood particleboard. A disadvantage of these adhesives, however, is that formaldehyde is emitted both during production of the particleboard and during use of the finished, pressed particleboard.
MDF and HDF are also produced using polymeric isocyanate (PMDI), as a binder to achieve better moisture properties.
In one manufacturing process for medium density fiberboard (MDF) and high density fiberboard (HDF), the fibers are typically hydrothermally pretreated in a first step in a refiner unit, i.e. boiled and milled at elevated temperature under steam pressure. After milling, the fibers, while still under steam pressure and at temperatures from 120° C. to 150° C., are treated with binder by spraying an aqueous dispersion of the binder via a cooled valve into the blow-line. The turbulence which occurs at a flow velocity of from 200 to 500 m/s distributes the binder uniformly over the fiber surface. Finally, the fibers which are treated with binder are dried, laid down uniformly, and pressed at temperatures of from 150 to 250° C. to produce boards.
A particularly important use of the particleboard, MDF, and/or HDF panels, is in the production of laminate flooring. As is known in the art, laminate flooring is made up of several layers typically including, for example, a decorative paper, a wear layer in melamine resin over the decorative paper, a core layer made of HDF, MDF or particleboard as a support layer, and a stabilizing layer made of paper. While the decorative paper is what gives the laminate flooring its individual appearance, the wear layer provided by the melamine resin provides a highly wear resistant material.
The core of the laminate floor, however, is provided by the core layer of particleboard, MDF and/or HDF which supports the decorative paper and the overlay.
A variety of other layers can be added to these materials, including a paper backing (or balancing layer) in order to produce laminate floors having different properties. The core layer of laminate flooring is typically produced in board form by pressing the materials together at high pressure and at high temperature.
However, a common problem of laminate flooring of the prior art, is the high sound levels measured from normal use of the flooring. Various approaches have been made to reduce the sound level including the use of a sound absorbing foam sublayer beneath the laminate floor. However, the prior art approaches do not address the real issue that the existing MDF, HDF and particleboard cores are not resilient and therefore, act to amplify the sound.
As such, typical opportunities for the resilient composite board of the present invention will include replacement for cork, acting as sound attenuating underlayment panels, linoleum replacement, and most particularly, acting as flexible and sound absorbing core materials for laminate floors or engineered wood floors, panel products for furniture and cabinetry, wall and ceiling panels and other architectural applications etc.
Accordingly, while being of some benefit, the prior art approaches can be expensive or time consuming, and as such, it would still be beneficial to provide a laminate material, and a method for the production of, a resilient core layer for use in a laminate material, which core layer provides sound attenuating properties.